Many proposals have been made for the use of solar energy as a thermal source or for conversion to electricity. Among the various systems proposed are parabolic reflectors for concentrating energy at a focus at which a heat collector or other utilization device is disposed. Other known systems have employed arrays of reflectors or lenses for energy concentration. In general, systems proposed heretofore have not been wholly satisfactory, usually by reason of cost and complexity of the structures employed. For example, parabolic reflectors, in order to provide useful concentration, are relatively large and require a precise parabolic surface. In addition, the heat collector must be supported at the focus of the parabolic surface by a support structure which can partially occlude incident energy. Lens systems are by their nature expensive to construct and maintain. It would be useful to have a solar energy concentrator which can be easily constructed of relatively inexpensive materials and without necessity for sensitive and precisely constructed optical elements.